A BOMB threat in Gaggenau sparked an evacuation just one day after a Turkish rally was cancelled as Ankara warned Germany to behave and threatened consequences for scrapping the event.

German authorities in the southwestern town of Gaggenau evacuated the city hall after receiving a bomb threat, its mayor told German television, one day after he cancelled an event where Turkey's justice minister was to speak.

The building was evacuated and police searched the city hall for more than three hours.

Asked by n-tv broadcaster if the bomb threat was linked to the cancellation of the Turkish minister's rally, Gaggenau mayor Michael Pfeiffer said: "We presume this at the moment, but we don't know for sure. We presume there is a direct link.

Police said they were called at around 8am local time following reports of a bomb threat. The area was sealed off but after a major search no explosives were found.

The threat comes as Turkey told Germany it must "learn how to behave" if it wanted to maintain relations after Gaggenau and Cologne stopped Turkish ministers speaking at meetings of supporters of President Tayyip Erdogan.

Gaggenau, a town in Rastatt in the south west of Germany, withdrew permission on Thursday for a meeting where Turkish minister Bekir Bozdag had been due to speak.

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Police outside the Festhalle Bad Rotenfels hall after a rally for expatriate Turks was cancelled